The renewal grant (HL-11880, 2/1/76) for which Supplemental funds are requested was organized into seven closely linked projects. Funds were requested for each of these but funding awarded was insufficient to permit us to support all of the projects proposed. One of the major areas in that renewal application (X-Ray spectrometry of platelets) required new instrumentation and technical support in order for us to carry out analytical electron microscopy. The items requested, amounting to about $70,000, were not awarded. Now, we no longer need to equip our own microscope for X-ray analysis. Last year, a combined effort by several departments, including our own, resulted in the purchase and installation of a JEOL 100CX analytical EM on our campus. We have been allowed access to this equipment since its arrival in order to demonstrate applicability to our work in preparation for this proposal. The results of our initial studies have been very successful, and, as indicated in detail in the body of this request, we now will be able to accomplish the goals of this project. However, it is essential that we acquire computer capability and technical support for carrying out these studies. We have also moved ahead in two other projects which require the technical support and computer requested here. In 1974 we introduced the use of high pressure liquid chromatography (HPLC) to study platelet adenine nucleotides. Results obtained with HPLC by ourselves and others have been very good and have virtually replaced other techniques. Data generated by these investigations of prostaglandin and nucleotide kinetics require careful computer analysis. A third area of our investigation on platelets is new and very exciting. The techniques of optical diffraction and Fourier analysis have not been employed in previous studies of blood platelets. We are using this technology in studies of neutrophil phagocytosis, in analysis of the organization in hemoglobin-S polymers, and are now employing the method in studies of filament organization during contractile events in activated platelets. Data generated in the form of optical transforms is complex and requires digital computer analysis for full interpretation. Thus, te three areas described above all require the availability of a mini computer system for data analysis and the necessary technical support.